1. Field of the Invention
The invention is directed to a rotor of a turbomachine.
2. Description of the Related Art
A rotor of a turbomachine, particularly of a gas turbine or steam turbine, has a rotor base body and a plurality of rotor blades that are fastened to the rotor base body. The rotor blades of the turbomachine rotor have a blade root and a blade body. Every rotor blade is fastened by its blade root to the rotor base body in a slot of the rotor base body in a mounting direction defined by the blade roots, and every rotor blade has in the region of its blade body at least one coupling element segment constructed as an outer shroud segment when this coupling element segment is positioned on the radially outer side of the blade body. The coupling element segments, particularly the outer shroud segments, of all of the rotor blades of a turbomachine rotor of this kind together form at least one circumferentially closed coupling element of the rotor, particularly an outer shroud.
Considered in circumferential direction of a turbomachine rotor, a width of a coupling element segment, particularly an outer shroud segment, of every rotor blade is defined by edges extending substantially in axial direction. A depth in axial direction of the coupling element segment, particularly of the outer shroud segment, of every rotor blade is defined by edges extending substantially in circumferential direction. Aside from the width in circumferential direction and the depth in axial direction, a coupling element segment, particularly an outer shroud segment, of every rotor blade is also characterized by a thickness in radial direction.
Turbomachine rotors whose rotor blades have coupling element segments of the type mentioned above for forming at least one coupling element can be installed in the region of the compressor as well as in the region of a turbine of the turbomachine.
Turbomachine rotors having rotor blades are fastened to their rotor base body and have at the radially outer side of the blade body a coupling element segment formed as an outer shroud segment are known, for example, from DE 1 159 965 C, DE 40 15 206 C1, U.S. Pat. No. 4,400,915 A, and GB 2 072 760 A. It is known from EP 1 134 359 A1 and DE 1 122 551 C to fasten the rotor blades by the blade roots to the rotor base body in a slot of the rotor base body in a mounting direction defined by the blade roots. The blade roots can have a fir-tree contour, a hammerhead contour, or a contour of another kind. A separate slot can be provided at the rotor base body for each blade root. Further, it is possible for all of the blade roots to be fastened in a common slot and to be threaded into this common slot through an insertion opening and, in this way, mounted at the rotor base body.
The coupling elements of turbomachine rotors of the type mentioned above formed as outer shroud segments are exposed to high loads in operation because they rotate at maximum radius with respect to an axis of rotation of the turbomachine rotor and are therefore exposed to high centrifugal forces. As a result of the centrifugal load, corners and edges of the coupling element segments of the rotor blades bend outward so that on the one hand stress peaks are caused in the coupling element and on the other hand a desired contact between adjacent coupling element segments of adjacent rotor blades is reduced to punctiform contact or disappears entirely. This reduces or eliminates a desired coupling between adjacent coupling element segments so that the vibration behavior of the turbomachine rotor eventually deteriorates.